The long-term objective of this proposal is the methodology development and manufacturing of antithrombogenic surfaces containing poly(ethylene oxide)- tethered bioactive compounds that counteract or inhibit the major thrombogenic effects known to occur when a surface is exposed to blood. The specific aims of the Phase I research are to (a) produce and characterize in detail heparin-only and urokinase-only surfaces in terms of total bioactives and surface bioactivity, and this information will be used to; (b) develop methodology to produce heparin-urokinase surfaces, which would be evaluated for bioactivity and antithrombogenicity and compared to the control surfaces produced in (a). Bisfunctional poly(thylene oxide) (PEO) will be coupled to surface amino groups. Bioactive molecules will be coupled via amino groups to the surface bound PEO under aqueous conditions. Analysis of radiolabelled surfaces will be used to determine total amount of immobilized bioactive molecules, and bioassay procedures that have been modified for surface immobilized compounds will be used to determine their bioactivity at the interface. Methodology for manufacture of multifunctional antithrombogenic surfaces under controlled conditions would significantly extend the existing technology available for treating blood- contacting devices to render them antithrombogenic and thus more hemocompatible.